Skip to content
Breastfeeding MomHealthy Babies. Confident Moms.

Breast Milk Storage Calculator: Is My Milk Still Good?

Enter when your milk was pumped or thawed and where it's stored, and see the exact date and time to use it by, based on CDC guidelines.

Use by

–

Choose the type of milk, where it is stored and when it was expressed.

This breast milk storage calculator tells you exactly when expressed milk should be used by. Choose whether the milk is fresh, thawed or left over from a feed, pick where it’s stored and enter when it was expressed (or thawed, or when the feed ended). The calculator applies the CDC storage guidelines for healthy, full-term babies and shows the use-by date and time, plus whether the milk is still within the recommended window.

For the reasons behind these times, how to store milk well and how to save freezer space, read our complete breast milk storage guide.

CDC breast milk storage times

Type of milk Room temperature (up to 77°F / 25°C) Refrigerator (40°F / 4°C) Freezer (0°F / -18°C or colder)
Freshly expressed Up to 4 hours Up to 4 days Within 6 months is best; up to 12 months is acceptable
Thawed (previously frozen) 1–2 hours Up to 1 day (24 hours) Never refreeze thawed milk
Left over from a feeding Use within 2 hours after the baby finishes

In an insulated cooler with frozen ice packs, freshly expressed milk keeps for up to 1 day, for example while you travel home from work.

How the calculator works

The calculator adds the CDC storage time for your situation to the time you enter:

  • Fresh milk: from the moment it was expressed.
  • Thawed milk: from the moment it was fully thawed (no ice crystals left). That’s why the fridge window for thawed milk is 24 hours even if the milk took a day to thaw.
  • Leftover milk: from the moment your baby finishes feeding. Bacteria from your baby’s mouth get into the bottle, so leftover milk can’t be saved for later.

For frozen milk, it also shows the “best quality” date (6 months) and the latest acceptable date (12 months). Frozen milk doesn’t go bad at 6 months, but some fats and vitamins slowly break down, so use your oldest milk first.

Worked examples

  • Pumped Monday at 8:00 a.m., kept in the fridge: use by Friday at 8:00 a.m.
  • Pumped at 2:00 p.m., left on the counter: use by 6:00 p.m. the same day.
  • Frozen on January 15: best by July 15, acceptable until January 15 of the next year.
  • Thawed in the fridge, fully liquid at 7:00 p.m. Tuesday: use by 7:00 p.m. Wednesday.
  • Baby stopped drinking a bottle at 10:30 a.m.: use the rest by 12:30 p.m., then throw it away.

Want to know how to safely bring milk back to temperature? See how to thaw frozen breast milk and how to warm breast milk.

Tips to make your milk last

  • Cool it fast. Put fresh milk in the fridge or a cooler with ice packs as soon as you can.
  • Store it in the back. The fridge or freezer door warms up every time it’s opened.
  • Label everything. Write the date (and time, for fridge milk) on every bag or bottle.
  • Freeze in small portions. 2 to 4 oz portions thaw faster and waste less.
  • Leave room to expand. Milk expands as it freezes, so don’t fill containers to the top.
  • Trust your nose too. Milk that smells sour or spoiled should be thrown away, even if it’s within the time limit. A soapy smell after freezing is usually harmless (it can be caused by an enzyme called lipase).

Limits of this calculator

The times apply to healthy, full-term babies at home. Follow your hospital’s instructions if your baby is premature or ill. If your power went out or your milk may have warmed up, use the shortest storage time that applies, and when in doubt, throw it out. This calculator does not replace advice from your pediatrician or lactation consultant.

Frequently asked questions

How long is breast milk good for in the fridge?

Freshly expressed breast milk can be kept in the refrigerator for up to 4 days. Milk that was frozen and then thawed in the fridge should be used within 24 hours of being fully thawed.

How long can breast milk sit out at room temperature?

Freshly expressed milk can stay at room temperature (up to 77°F / 25°C) for up to 4 hours. Thawed milk is good for only 1 to 2 hours at room temperature, and milk left over after a feed must be used within 2 hours.

Does the clock start when I pump or when I put the milk in the fridge?

The times count from when the milk was expressed. Time spent at room temperature before refrigerating counts too, so cool milk quickly and, when in doubt, use the earlier time.

Can I combine milk from different pumping sessions?

Yes. Cool the freshly pumped milk in the fridge first, then add it to milk that is already cold, and use the date of the oldest milk for the whole container.

Do these times apply to premature or hospitalized babies?

No. The CDC times are for healthy, full-term babies at home. If your baby is premature, sick or in the hospital, follow the storage instructions from your baby's care team, which are often stricter.

Sources

  1. CDC: Proper Storage and Preparation of Breast Milkhttps://www.cdc.gov/breastfeeding/breast-milk-preparation-and-storage/handling-breastmilk.html
  2. Academy of Breastfeeding Medicine Clinical Protocol #8: Human Milk Storage Information for Home Use for Full-Term Infants (2017)https://www.bfmed.org/protocols
  3. AAP HealthyChildren.org: Storing and Preparing Expressed Breast Milkhttps://www.healthychildren.org/English/ages-stages/baby/breastfeeding/Pages/Storing-and-Preparing-Expressed-Breast-Milk.aspx

This guide is general information, not medical advice. For your own situation, talk to your doctor, midwife, pharmacist or an IBCLC lactation consultant. Read our medical disclaimer and find breastfeeding support near you.

Related articles